Semiconductor switching elements can be used as switches for switching electrical loads. Such semiconductor switching elements are, e.g., MOS transistors, such as MOSFET or IGBT. For driving the semiconductor switching elements in the on state or in the off state drive circuits are used, the drive circuits being connected to a drive terminal of the semiconductor switching element and requiring a supply voltage for providing a drive signal for the semiconductor switching element.
Drive circuits for semiconductor switching elements, which have to be able to provide a floating drive voltage for the semiconductor switching element, accordingly require a floating supply voltage. Such drive circuits are, e.g., the drive circuits of n- or p-conducting MOSFETs, or of IGBTs, which are interconnected as high-side switches.
For providing a floating supply voltage for drive circuits of semiconductor switching elements, bootstrap circuits may be used, for example. Further, transformers may be used that convert a supply voltage referred to a reference potential to a desired supply voltage.
For these and other reasons there is a need for the present invention.